The invention relates to a system and a method for returning exhaust gases to a combustion chamber, primarily for use with a motor vehicle having an internal combustion engine. The primary purpose of returning the exhaust gases is to increase the fuel economy of, or decrease the pollutants emitted from, the combustion chamber.
An exemplary prior system for recirculating exhaust gases is disclosed in U.S. Pat. No. 4,114,370, which includes a system for separating out desirable gases, filtering the gases, and returning the filtered gases to the intake manifold of an internal combustion engine. Additionally, excess liquid may be vaporized in such a system and also returned to the engine.
While the system described in U.S. Pat. No. 4,114,370 is generally successful, there are a number of practical problems associated therewith, mostly related to problems of constucting the components. For instance, the skimmer is difficult to mass produce efficiently, and the installation of the skimmer with the U-shaped, square-cornered clarifier is time consuming. Also, with many internal combustion engines for motor vehicles the system produces excess liquid that must somehow be disposed of, otherwise the improved operation desired by employing this system may be somewhat diminished.
According to the present invention, a system and method are provided that eliminate most or all of the problems mentioned above. In particular, the system according to the present invention is simple to mass produce, installation time is much reduced (by as much as 300%), and excess liquid is not produced. In addition, the filters associated with the system according to the invention last longer and may be simply cleaned with soap and reused, rather than having to be entirely replaced as was often necessary in prior systems. Also, the system according to the invention is as effective as the prior systems for increasing fuel economy and/or decreasing pollutants.
An exemplary system according to the present invention comprises an exhaust conduit from a combustion chamber having a first portion disposed in a substantially straight line; an expansion chamber connected in a straight line with the exhaust conduit first portion at a first end thereof, and having a second end, opposite the firt end; and a second substantially straight line portion of the exhaust conduit connected in a straight line with the expansion chamber second end. The expansion chamber has a larger cross-sectional area than the exhaust conduit first or second portions (preferably 110% to 200% larger). Means are provided for defining a plurality of openings in the expansion chamber in first and second series, the first series disposed substantially 180.degree. from the second series along the circumference of the expansion chamber. Means are provided for mounting the expansion chamber so that a plane containing the first and second series of openings in the expansion chamber is generally vertical. Pick off conduit means are operatively associated with the openings in the expansion chamber and for returning gases passing through the openings from the expansion chamber to the combustion chamber, filtering means being disposed in the conduit means between the expansion chamber and the combustion chamber for, at least, separating excess liquid out of the returning gases.
The openings in the expansion chamber are each disposed along a line making an acute angle with respect to a line concentric with the expansion chamber and leading from the first exhaust conduit portion to the second exhaust conduit portion. The means defining the plurality of openings preferably defines four openings in each series, comprising first, second, third and fourth openings. The first opening in each series is closest to the exhaust conduit first portion, with the second, third and fourth openings extending in order therefrom. The first and fourth openings are preferably disposed along a straight line substantially parallel to the straight line between the expansion chamber and the exhaust conduit first portion, and the second and third openings are disposed on opposite sides of that straight line between the first and fourth openings. The second and third openings do not overlap the first and fourth openings either in the dimension of the straight line or in a dimension perpendicular to the straight line. The second and third openings are disposed no more than 20.degree. from the straight line along the circumference of the expansion chamber. In an exemplary system according to the present invention, for use with a 351 cubic inch Ford engine, the length of the expansion chamber from the first exhaust conduit to the first opening in series is 10.5 inches, the length from the fourth opening in each series to the second exhaust conduit is 3 inches, and there is a spacing of approximately 11/2 inches between the openings along the dimension of the straight line, each opening having a diameter of about 5/8 to 5/16 inches.
The filtering means utilized in practicing the invention preferably comprise a first substantially horizontally disposed filter having a top gas containing portion, and a lower liquid separating portion, and a second substantially vertically disposed filter disposed vertically above the first filter and a conduit interconnecting the filters to allow excess liquid in the second filter to drain into the first filter. The first filter has a liquid conduit extending from the lower portion thereof through means for vaporizing the liquid therewithin to the engine intake manifold. The conduit interconnecting the filters extends from the first filter top portion to a bottom portion of the second filter, and another conduit extends from a top portion of the second filter to the intake manifold. The filters preferably are tubes made of aluminum, with aluminum mesh disposed in the lower portion of the first filter and a lower portion of the second filter.
An exemplary method of acting upon exhaust gases from an internal combustion engine having an intake manifold, and utilizing an exhaust conduit and a generally horizontally disposed expansion chamber, according to the present invention consists essentially of the following steps: (a) Passing the exhaust gas from the internal combustion engine through the exhaust conduit in a generally horizontal direction. (b) Generally transforming turbulent circular motion of gases within the exhaust conduit into a more linear pressure flow (as by passing the exhaust gases through a muffler connected in substantially a straight line with the expansion chamber). (c) In the expansion chamber, effecting separation of primarily hydrocarbon gases, carbon monoxide, and water vapor from the more linear pressure flow. (d) Collecting the separated gases and returning them toward the internal combustion engine. (e) Filtering the returning gases to, at least in part, separate out excess liquid. (f) Delivering hydrocarbon and/or carbon monoxide having a relative humidity of 60 to 100% to the intake manifold; and (g) vaporizing excess liquid separated from the returning gases and returning the vapor so formed to the intake manifold.
It is the primary object of the present invention to provide a simple to manufacture and install exhaust gas treatment system for a combustion chamber, and associated method, which can increase the fuel economy of and/or decrease the pollutants from, a combustion chamber. This and other objects of the invention will become clear from an inspection of the detailed description of the drawings, and from the appended claims.